EFFECT OF EXCRETION PRODUCTS OF PARAMAECIUM 



575 



Fig. 7 Record of experiments on the effect of changing the culture medium at 

 twenty-four-hour intervals and at forty-eight-hour intervals, when Paramaecium 

 aurelia is bred in twenty drops of hay infusion. The ordinates represent the aver- 

 age daily rate of division of the four lines of organisms, again averaged for four 



day periods. Medium changed at twenty-four-hour intervals = ; changed at 



forty-eight-hour intervals = . 



Fig. 8 Record of experiments on the effects of changing the culture medium at 

 twenty-four-hour intervals and at forty-eight- hour intervals, when Paramaecium 

 aurelia is bred in forty drops of hay infusion. The ordinates represent the average 

 daily rate of division of the four lines of organisms, again averaged for four day 



periods. Medium changed at twenty-four-hour intervals; = ; changed at 



forty-eight-hour intervals = . 



